Beer spoilage organisms

Occurrence and detection with particular reference to a new genus Pectinatus: Dissertation

Auli Haikara

Research output: ThesisDissertationCollection of Articles

Abstract

Lactic acid bacteria of the genera Lactobacillus and Pediococcus, acetic acid bacteria, enterobacteria and wild yeasts of the genus Saccharomyces are regarded as the most harmful beer spoilage organisms due to their ability to cause off-flavours and/or turbidity in beer.The investigation concerning the microbiological status of Finnish breweries revealed that the most frequent contaminant during fermentation was Pediococcus damnosus.Enterobacter agqlomerans was detected in the few brews in which heavy contaminations of Gram-negative species were found.The most frequent source of contamination was the pitching yeast, especially old yeast which had been used in several fermentations.Growth of bacteria occured mainly in yeast storage vessels.Worts were generally free of bacteria and only very low counts of microorganisms were detected in packaged beer.Reasonably low levels of wild yeasts were found in all stages of the brewing process.In general the microbiological status of the breweries investigated was highly satisfactory.In addition to conventional plating methods with selective media, rapid methods based on the use of fluorescing dyes were investigated.The immunofluorescence technique was applied for the detection of wild yeasts in pitching yeast and the microcolony method with optical brighteners was developed for the enumeration of yeasts and bacteria in packaged beer.A new Gram-negative, strictly anaerobic beer spoilage bacterium Pectinatus cerevisiophilus was isolated from turbid beer.The morphological, physiological, biochemical and electron microscopic characterization of this organism revealed only small differences between the Pectinatus isolates studied.The location of flagella on one side of the cell is a distinctive feature of P. cerevisiophilus.Propionic acid, which is the main metabolic product, was produced via the succinate pathway also used by propionibacteria.The formation of other orsanic acids and sulphur compounds resulted in the spoilage of beer f lavour.The cell envelope structure in thin section revealed a thick peptidoglycan layer below the outer membrane and invaginations and mesomes from the cytoplasmic membrane.These are all features normally regarded as typical Gram-positive bacteria. Freezefractured micrographs on the other hand revealed the typical outer membrane of Gram-negative bacteria, with small intramembranous particles (8 - l0 nm).The large intramembranous particles (20 nm) found in the concave faces of the outer and cytoplasmic membranes have not been observed previously in any organisms.On the basis of the immunological characterization using gel-diffusion precipitin tests and immunoelectrophoresis the eleven Pectinatus isolates studied could be assigned to three distinct groups.The chemical composition of the lipopolysaccharides of the Pectinatus isolates revealed an identical fatty acid pattern, indicating that they all belong to a taxonomically homogeneous group.Moreover, the flatty acid composition of Pectinatus isolates distinguishes them from most other groups of Gram-negative bacteria.This, along with the location of flagella, the pathway of propionic acid formation and immunological properties, justifies the separate taxonomic status of this genus.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Helsinki
Award date16 Mar 1984
Place of PublicationEspoo
Publisher
Print ISBNs951-38-1961-2
Publication statusPublished - 1984
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

Pectinatus
beers
spoilage
new genus
yeasts
organisms
brewing industry
propionic acid
flagellum
Gram-negative bacteria
cell membranes
bacteria
Pediococcus damnosus
fermentation
precipitin tests
acetic acid bacteria
Propionibacterium
Pediococcus
immunoelectrophoresis
Enterobacter

Keywords

  • contamination
  • Pectinatus
  • beer
  • microbiology

Cite this

Haikara, Auli. / Beer spoilage organisms : Occurrence and detection with particular reference to a new genus Pectinatus: Dissertation. Espoo : VTT Technical Research Centre of Finland, 1984. 111 p.
@phdthesis{b4ad68f7b6634a18bfe7613e7d20c563,
title = "Beer spoilage organisms: Occurrence and detection with particular reference to a new genus Pectinatus: Dissertation",
abstract = "Lactic acid bacteria of the genera Lactobacillus and Pediococcus, acetic acid bacteria, enterobacteria and wild yeasts of the genus Saccharomyces are regarded as the most harmful beer spoilage organisms due to their ability to cause off-flavours and/or turbidity in beer.The investigation concerning the microbiological status of Finnish breweries revealed that the most frequent contaminant during fermentation was Pediococcus damnosus.Enterobacter agqlomerans was detected in the few brews in which heavy contaminations of Gram-negative species were found.The most frequent source of contamination was the pitching yeast, especially old yeast which had been used in several fermentations.Growth of bacteria occured mainly in yeast storage vessels.Worts were generally free of bacteria and only very low counts of microorganisms were detected in packaged beer.Reasonably low levels of wild yeasts were found in all stages of the brewing process.In general the microbiological status of the breweries investigated was highly satisfactory.In addition to conventional plating methods with selective media, rapid methods based on the use of fluorescing dyes were investigated.The immunofluorescence technique was applied for the detection of wild yeasts in pitching yeast and the microcolony method with optical brighteners was developed for the enumeration of yeasts and bacteria in packaged beer.A new Gram-negative, strictly anaerobic beer spoilage bacterium Pectinatus cerevisiophilus was isolated from turbid beer.The morphological, physiological, biochemical and electron microscopic characterization of this organism revealed only small differences between the Pectinatus isolates studied.The location of flagella on one side of the cell is a distinctive feature of P. cerevisiophilus.Propionic acid, which is the main metabolic product, was produced via the succinate pathway also used by propionibacteria.The formation of other orsanic acids and sulphur compounds resulted in the spoilage of beer f lavour.The cell envelope structure in thin section revealed a thick peptidoglycan layer below the outer membrane and invaginations and mesomes from the cytoplasmic membrane.These are all features normally regarded as typical Gram-positive bacteria. Freezefractured micrographs on the other hand revealed the typical outer membrane of Gram-negative bacteria, with small intramembranous particles (8 - l0 nm).The large intramembranous particles (20 nm) found in the concave faces of the outer and cytoplasmic membranes have not been observed previously in any organisms.On the basis of the immunological characterization using gel-diffusion precipitin tests and immunoelectrophoresis the eleven Pectinatus isolates studied could be assigned to three distinct groups.The chemical composition of the lipopolysaccharides of the Pectinatus isolates revealed an identical fatty acid pattern, indicating that they all belong to a taxonomically homogeneous group.Moreover, the flatty acid composition of Pectinatus isolates distinguishes them from most other groups of Gram-negative bacteria.This, along with the location of flagella, the pathway of propionic acid formation and immunological properties, justifies the separate taxonomic status of this genus.",
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author = "Auli Haikara",
year = "1984",
language = "English",
isbn = "951-38-1961-2",
series = "Publications / Technical Research Centre of Finland",
publisher = "VTT Technical Research Centre of Finland",
number = "14",
address = "Finland",
school = "University of Helsinki",

}

Beer spoilage organisms : Occurrence and detection with particular reference to a new genus Pectinatus: Dissertation. / Haikara, Auli.

Espoo : VTT Technical Research Centre of Finland, 1984. 111 p.

Research output: ThesisDissertationCollection of Articles

TY - THES

T1 - Beer spoilage organisms

T2 - Occurrence and detection with particular reference to a new genus Pectinatus: Dissertation

AU - Haikara, Auli

PY - 1984

Y1 - 1984

N2 - Lactic acid bacteria of the genera Lactobacillus and Pediococcus, acetic acid bacteria, enterobacteria and wild yeasts of the genus Saccharomyces are regarded as the most harmful beer spoilage organisms due to their ability to cause off-flavours and/or turbidity in beer.The investigation concerning the microbiological status of Finnish breweries revealed that the most frequent contaminant during fermentation was Pediococcus damnosus.Enterobacter agqlomerans was detected in the few brews in which heavy contaminations of Gram-negative species were found.The most frequent source of contamination was the pitching yeast, especially old yeast which had been used in several fermentations.Growth of bacteria occured mainly in yeast storage vessels.Worts were generally free of bacteria and only very low counts of microorganisms were detected in packaged beer.Reasonably low levels of wild yeasts were found in all stages of the brewing process.In general the microbiological status of the breweries investigated was highly satisfactory.In addition to conventional plating methods with selective media, rapid methods based on the use of fluorescing dyes were investigated.The immunofluorescence technique was applied for the detection of wild yeasts in pitching yeast and the microcolony method with optical brighteners was developed for the enumeration of yeasts and bacteria in packaged beer.A new Gram-negative, strictly anaerobic beer spoilage bacterium Pectinatus cerevisiophilus was isolated from turbid beer.The morphological, physiological, biochemical and electron microscopic characterization of this organism revealed only small differences between the Pectinatus isolates studied.The location of flagella on one side of the cell is a distinctive feature of P. cerevisiophilus.Propionic acid, which is the main metabolic product, was produced via the succinate pathway also used by propionibacteria.The formation of other orsanic acids and sulphur compounds resulted in the spoilage of beer f lavour.The cell envelope structure in thin section revealed a thick peptidoglycan layer below the outer membrane and invaginations and mesomes from the cytoplasmic membrane.These are all features normally regarded as typical Gram-positive bacteria. Freezefractured micrographs on the other hand revealed the typical outer membrane of Gram-negative bacteria, with small intramembranous particles (8 - l0 nm).The large intramembranous particles (20 nm) found in the concave faces of the outer and cytoplasmic membranes have not been observed previously in any organisms.On the basis of the immunological characterization using gel-diffusion precipitin tests and immunoelectrophoresis the eleven Pectinatus isolates studied could be assigned to three distinct groups.The chemical composition of the lipopolysaccharides of the Pectinatus isolates revealed an identical fatty acid pattern, indicating that they all belong to a taxonomically homogeneous group.Moreover, the flatty acid composition of Pectinatus isolates distinguishes them from most other groups of Gram-negative bacteria.This, along with the location of flagella, the pathway of propionic acid formation and immunological properties, justifies the separate taxonomic status of this genus.

AB - Lactic acid bacteria of the genera Lactobacillus and Pediococcus, acetic acid bacteria, enterobacteria and wild yeasts of the genus Saccharomyces are regarded as the most harmful beer spoilage organisms due to their ability to cause off-flavours and/or turbidity in beer.The investigation concerning the microbiological status of Finnish breweries revealed that the most frequent contaminant during fermentation was Pediococcus damnosus.Enterobacter agqlomerans was detected in the few brews in which heavy contaminations of Gram-negative species were found.The most frequent source of contamination was the pitching yeast, especially old yeast which had been used in several fermentations.Growth of bacteria occured mainly in yeast storage vessels.Worts were generally free of bacteria and only very low counts of microorganisms were detected in packaged beer.Reasonably low levels of wild yeasts were found in all stages of the brewing process.In general the microbiological status of the breweries investigated was highly satisfactory.In addition to conventional plating methods with selective media, rapid methods based on the use of fluorescing dyes were investigated.The immunofluorescence technique was applied for the detection of wild yeasts in pitching yeast and the microcolony method with optical brighteners was developed for the enumeration of yeasts and bacteria in packaged beer.A new Gram-negative, strictly anaerobic beer spoilage bacterium Pectinatus cerevisiophilus was isolated from turbid beer.The morphological, physiological, biochemical and electron microscopic characterization of this organism revealed only small differences between the Pectinatus isolates studied.The location of flagella on one side of the cell is a distinctive feature of P. cerevisiophilus.Propionic acid, which is the main metabolic product, was produced via the succinate pathway also used by propionibacteria.The formation of other orsanic acids and sulphur compounds resulted in the spoilage of beer f lavour.The cell envelope structure in thin section revealed a thick peptidoglycan layer below the outer membrane and invaginations and mesomes from the cytoplasmic membrane.These are all features normally regarded as typical Gram-positive bacteria. Freezefractured micrographs on the other hand revealed the typical outer membrane of Gram-negative bacteria, with small intramembranous particles (8 - l0 nm).The large intramembranous particles (20 nm) found in the concave faces of the outer and cytoplasmic membranes have not been observed previously in any organisms.On the basis of the immunological characterization using gel-diffusion precipitin tests and immunoelectrophoresis the eleven Pectinatus isolates studied could be assigned to three distinct groups.The chemical composition of the lipopolysaccharides of the Pectinatus isolates revealed an identical fatty acid pattern, indicating that they all belong to a taxonomically homogeneous group.Moreover, the flatty acid composition of Pectinatus isolates distinguishes them from most other groups of Gram-negative bacteria.This, along with the location of flagella, the pathway of propionic acid formation and immunological properties, justifies the separate taxonomic status of this genus.

KW - contamination

KW - Pectinatus

KW - beer

KW - microbiology

M3 - Dissertation

SN - 951-38-1961-2

T3 - Publications / Technical Research Centre of Finland

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -